| 摘要 |
To simplify fitting and sealing the crystal (4) to the casing (2, 6, 8), assembly is effected by means of ultrasonic welding. The casing (2, 6, 8) and the crystal (4) are made of synthetic materials which are thermo-weldable to each other. The mating faces (8a, 4b) of the peripheral wall (8) of the casing and the crystal (4) are formed for reducing the contact area between the two parts to permit thermo-welding by subjecting the assembly to high-frequency mechanical vibrations imparted by a tool (15). |
